Vapor generators



Dec. 16, 1958 C ARTSAY 2,864,344

VAPOR GENERATORS Filed June 30. 1954 INVENTOR MCI-101.46 6. Aer-5m BY 85 W ATTORNE United States Patent VAPOR GENERATORS Nicholas C. Artsay, Valhalla, N. Y., assignor to Foster Wheeler Corporation, New York, N. Y., a corporation of New York 1 Application June 30, 1954, Serial No. 440,508

6 Claims. (Cl. 122-494 The present invention relates to vapor generators and more particularly to a vapor generator operating at combustion gas pressure above atmospheric pressure.

In a vapor generator, operated at combustion gas pressure above atmospheric pressure, there are numerous tube openings in the walls of the generator through which metal tubes extend to certain elements outside the walls. Due to contraction and expansion of these tubes caused by temperature changes, the tube openings cannot be made air-tight and hence combustion gases escape to the surrounding boiler room which is under atmospheric pressure. To prevent gases from escaping to the boiler room where they may cause a fire or injure personnel, an airtight casing is provided to completely enclose the vapor generator. The disadvantage of the air tight casing is that the combustion gas pressure in a vapor generator varies with the steam generating load and combustion gases continuously leave the vapor generator and enter the casing causing ash and soot to accumulate in the casing.

.In accordance with the present invention, novel means are provided to maintain a higher fluid pressure in the casing than the combustion gas pressure in the vapor generator to prevent fly ash and soot from entering the casing.

The present invention provides means for maintaining a pressure diiferential between the vapor generator and easing with a higher fluid pressure in the casing than the combustion gas pressure in the vapor generator.

Fig. 1 is a diagrammatic view in vertical section 'of a vapor generator embodying the present invention; and

Fig. 2 is an enlarged detail of the control means of Fig. 1 and embodied in the present invention.

Like characters of reference refer to the same or to similar parts throughout the several views.

Referring to the drawing, the reference numeral 10 designates the setting of a vapor generator with a gas side 10' having front and rear walls 11 and 12, a side wall 13, another side wall (not shown) opposite wall 13, a roof 14, and a hopper shaped floor 15 with a rearwardly extending horizontal portion 16 joining wall 12. Gas side 10 includes a furnace or combustion chamber 17 therein, lined by walls of riser or water tubes 19, 20, 21 and another wall of water tubes (not shown) opposite tubes 21. Tubes 19 are connected at their lower ends to a header 22 adjacent the lower portion of floor 15 outside setting 10. The upper ends of tubes 19 are connected to a steam and water drum 23 above roof 14 substantially in alignment with tube wall 20. Tubes 19 line the gas side 10' of front wall 11, and a portion of floor 15, and roof 14 adjacent the wall. Tubes 20 are connected at their lower ends to a header 24 adjacent the lower portion of floor 15 outside setting 10. The upper ends of tubes 20 are connected to drum 23. Tubes 20 line the gas side 10' of a rearward portion of floor 15 after which they extend substantially vertically upwardly to drum 23. A' gas outlet 20' is formed in chamber 17 by spacing the upper portions of tubes 20 laterally of one another. Headers 22 and 24 communicate with drum 23 by downcomer tubes 22' connected to a plurality of connecting tubes 24.

Tubes 24' enter the lower portion of drum 23. Tubes 21 line the gas side 10' of wall 13 and are connected at their lower ends to a header 25, adjacent floor 15 outside setting 10. The upper ends of tubes 21 are connected to a header 26 above roof 14. Header 26 communicates with drum 23 by a plurality of connecting tubes 27 while header communicates with the drum by downcomer tubes (not shown). Tubes (not shown), similar to wall tubes 21, line the side wall opposite wall 13, and are connected at their upper and lower ends to headers (not shown), similar to headers 25 and 26. The headers (not shown) are in communication with drum 23 by connecting tubes (not shown), similar to tubes 27, and by downcomer tubes (not shown). The lower portion of front wall 11 is provided with an air box 28 having a plurality of burners 29 therein for firing the furnace. Box 28 is supplied with combustion air by an air conduit 30 connected to fan 31. An ash outlet opening 32 is formed at the apex of hopper shaped floor 15 for removal of ashes from the furnace chamber. Opening 32 communicates with an ash removal passage 33 having an ash removal door (not shown).

A substantially vertical gas passage 34 is disposed within gas side 10 of the generator and communicates with chamber 17 through gas outlet opening 20'. Passage 34 extends horizontally in the setting, between the opposite side walls, and tube wall 20 and rear wall 12, and extends vertically between roof 14 and the horizontal portion 16 of floor 15. An outlet opening 35 is provided in the passage, adjacent floor portion 16, and communicates with the gas outlet of a stack (not shown).

Gas passage 34 has disposed therein a superheater 36, a reheater 37, a bare tube boiler section 38, and an economizer 39. Superheater 36 is positioned in the upper portion of passage 34 and is connected to an inlet header 40, located above roof 14, and an outlet header 41, positioned outside of wall 12. Header 40 communicates with drum 23 by a saturated vapor line (not shown) while outlet header 41 communicates with steam consuming apparatus (not shown).

Reheater 37 is disposed in passage 34 between superheater 36 and boiler section 38 and has inlet and outlet headers 42 and 43, respectively, disposed outside of wall 12. Headers 42 and 43 communicate with a steam turbine (not shown).

Boiler section 38 is positioned in passage 34 between reheater 37 and economizer 39, and communicates with drum 23 by water tubes 44 and a downcomer tube 45. Tubes 44 line the inside of wall 12 and downcomer tube 45 is connected to an inlet header 46 outside of wall 12.

Economizer 39 is positioned below boilersection 38 in passage 34 and has inlet and outlet headers 47 and 48, respectively, located outside of wall 12. Headers 47 and 48 are in communication with drum 23 and a source of feed water (not shown).

An air-tight Wall or casing 49 is positioned over roof 14 and completely encloses the tubes, headers, and drum above the roof. Casing 49 is joined along the lower edges thereof to the perimeter of roof 14 in fluid tight relationship and is coextensive therewith.

Another casing 50 is positioned around fioor 15 and completely encloses the tubes and headers located outside of floor 15. The upper edges of casing 50 are joined in fluid-tight relationship to the upper edges of floor 15 and to the side walls of chamber 17, adjacent said floor edges.

An air tight casing 51 is secured to the upper portion of the outside of rear wall 12 in a fluid-tight manner and encloses superheater outlet header 41 and reheater inlet and outlet headers 42 and 43. ,A casing 52 is secured to the lower portion of the wall in like manner and encloses boiler section inlet header 46 and economizer inlet and outlet headers 47 and 48.

Casing 49 is connected to an air supply line'53 having a damper 54 (Fig. 2) and an air discharge line 55 (Figs. 1 and 2) having a damper 56 (Fig. 2). Air discharge line 55 communicates with the atmosphere while supply line 53 is connected to an air manifold 57. Manifold 57 is supplied with air under pressure byranair conduit 58 connected to air fan 59. Dampers=54iand 56 are actuated by. damper actuating means 60 (shown in .detail in Fig. 2) which is responsive 'topressure control means 61, as hereinafter more fully described.

Referring to Fig. 2, a plate 62 has ends mounted on lines 53 and 55 and is provided with a central opening which accommodates an actuating rod 63 for slidable movement therein. A tension spring 63' is arranged about the upper part of rod 63 and'is held against plate 62 by threaded nut 62' on rod 63. The upper end of rod 63 is operably connected to pressure control means 61, as'hereinafter described, while the lower end of the rod is rigidly connected to a damper rod 64. The ends of damper rod 64 are provided with gear segments 65 and 66 Which mesh with damper gears 67 and 68, respectively. Gears 67 and 68 are disposed outside lines 53 and 55, respectively, and are fixedly connected to shafts 69 and 70 of dampers 54 and 56, respectively.

Pressure control'means 61 (Fig. 2) comprises a rigid pressure vessel 71 having a flexible metallic diaphragm 72 therein dividing the vessel into compartments 73 and 74. Vessel 71 is fixed to supports (not shown). Compartment 73 is in communication with casing 49 by a pressure line 75 while compartment 74 is in communication with the interior of setting 10, adjacent casing 49 by a pressure line 76. The upper end of rod 63 extends into compartment 74 of vessel 71 and is secured to diaphragm 72 which displaces rod 63 with changes in pressure in the compartments.

Casing 50 has connected thereto an air supply line 77 and an atmospheric discharge line 78 which lines have dampers (not shown) similar to the dampers in lines 53 and 55. Discharge line 78 communicates with the atmosphere, and supply line 77 communicates with manifold 57. Damper actuating means 79 and pressure control means 80 are provided for casing 50, both of which means are substantially similar in structure to the damper actuating means and control means heretofore described for casing-49. Control means 80 is connected by pressure lines 81 and 82, respectively, with the interior of casing 50 and with settinglt).

Casing 51 is connected to manifold 57 by an air supply line 83 and to the atmosphere by a line 84. A damper (not shown) is provided in each of lines 83 and 84 and the dampers are operated by actuating means 85, responsive to pressure control means 86. Control means 86 communicates with casing 51 and the interior of setting 10 through pressure lines 87 and 88 respectively.

Actuating means and control means 86 are substantially similar in structure to the actuating and pressure means of casing 49.

Casing 52 communicates with manifold 57 and with the atmosphere by way of lines 89 and 90, respectively, and the lines have dampers therein (not shown). The dampers are operated by actuating means 91, the operation of which is controlled by pressure control means 92; which means are substantially the same as those above described for casing 49. Control means 92 has pressure lines 93 and 94, respectively, in communication with the interior of casing'52 and with setting 10.

In operation, combustion air, at a pressure above atmospheric pressure, is supplied to burners 29 and the gaseous products of combustion produced in furnace 17 pass upwardly in heat exchange relationship with the water wall tubes lining the furnace. The gases thereafter pass out of the furnace through gas outlet opening 20' into gas passage 34. In passage 34, the gases pass downwardly in heat exchange relationship with superheater 36, reheater 37, boiler section 38, and economizer 39 disposed therein, the gases thereafter passing out the bottom of the passage through gas passage outlet 35 to a stack (not shown).

The gases in the vapor generator are prevented from passing through the numerous tube openings in setting 10 into casings 49, 50, 51 and 52 by maintaining a higher pressure in said casings than the combustion gas pressure in the adjoining positions of the setting. Thus, fly ash and soot are prevented from accumulating in the casings, which accumulation occurs in the conventional vapor generator when the gases enter the casings from the vapor generator.

The present invention contemplates the maintenance of a higher pressure in the interior of casing 49 than on the gas side 10' of the adjacent setting. To this end, diaphragm 72 and rod 63 are pre-set to a position corrcsponding to a desired differential pressure which is to be maintained across the portion of setting 10 adjoining casing 49. Diaphragm 72 is pre-set by threading nut 62 on rod 63. In this particular instance, since it is desired to maintain a higher pressure in casing 49, nut 62 is threaded in a direction to compress spring 63' which 'in turn causes diaphragm 72 to be flexed upwardly. When the values of the pressures in compartments 73 and 74 are such as to effect the desired differential pressure, diaphragm 72 will be returned to its original position as seen in the drawing. Thus, when the desired differential pressure is existent, damper 54 is arranged in a partially opened position in supply line 53 so that casing 49 receives a supply of air from fan 59, while damper 56 is arranged in a partially opened position in discharge line 55 so that a small amount of air in casing 49 is discharged to the atmosphere.

When the combustion gas pressure in the vapor generator setting decreases, the decrease in pressure is transmitted'by pressure line 76 to compartment 74 and the lower side of diaphragm 72 of vessel 71. The pressure in the interior of casing 49 is transmitted by pressure line 75 to compartment73 and the upper side of diaphragm 72. As the pressure in setting 10 decreases, diaphragm 72 is displaced downwardly which in turn moves rod 63 downwardly. Rod 64 being connected to rod 63 is also displaced downwardly together with gear segments 65 and 66. Gear segment 65 rotates damper gear 67 in a counterclockwise direction moving damper 54 to a closed position, as shown in Fig. 2, to shut off the supply of air from fan 59 to casing 49. Gear segment 66 rotates damper gear 68 in a clockwise direction moving damper 56 to an opened position, as shown in Fig. 2, to permit more air to escape from the interior of casing 49 to the atmosphere. Thus, the pressure in casing 49 is decreased. When the desired differential pressure is attained, diaphragm 72 is returned to its normal position.

When the pressure in setting 10 increases, the increase in pressure is transmitted by pressure line 76 t0 compartment 74 and the lower side of diaphragm 72 of vessel 71 to cause flexing of diaphragm 72 and of rod 63 upwardly. Rod 64 and gear segments 65 and 66 therefore move upwardly to rotate gears 67 and 68, respectively. Gear segment 65 rotates gear 67 in a clockwise direction to rotate damper 54 toward an opened position and to thereby permit air to be supplied from fan 59 to casing 49 which increases the pressure in the casing. Gear segment 66 rotates gear 68 in a counterclockwise direction to rotate damper 56 toward a closed position and to thereby shut off communication of the interior of casing 49 with the atmosphere, thereby increasing the casing pressure.

The damper actuating means 79 and pressure control means 80 for casing 50, actuating means 85 and pressure control means 86 for casing 51, and actuating means 91 and control means 92 for casing 52, operate in the same manner as actuating means 60 and pressure control means 61; as described above for casing 49.

Inasmuch as various changes may be made in the particular form, location and arrangement of the parts of the apparatus as disclosed without departing from the principles of the invention, it will be understood that the invention is not to be limited excepting by the scope of the appended claims.

What is claimed is:

1. In a vapor generator, a setting having a gas outlet opening therein, a furnace in the setting, means for firing the furnace, said furnace having a gas outlet opening therein, a gas passage in the setting in communication with said furnace gas outlet and setting gas outlet, tubular means in the setting disposed in heat exchange relationship with gases of combustion passing to said setting gas outlet, a portion of said tubular members extending outside said setting, an air-tight casing enclosing the portion of said tubular members extending outside said setting, a source of fluid under pressure, fluid supply means in communication with said fluid source and easing, fluid discharge means in communication with said casing and the atmosphere, damper means for controlling the flow of fluid through said fluid supply means, other damper means for controlling the flow of fluid through said fluid discharge means, and pressure control means for operating both said damper means to maintain a desired pressure differential between said casing and setting, said pressure control means being adapted to move the first- .mentioned damper means to an opened position and said other damper means to a closed position when the desired ,pressure differential changes by reason of an increase in pressure in the setting, and adapted to move said firstmentioned damper means to a closed position and said other damper means to an opened position when the desired pressure differential changes by reason of a decrease in pressure in the setting.

2. In a vapor generator, a setting having a gas outlet opening therein, a furnace in the setting, means for firing the furnace, said furnace having a gas outlet opening therein, a gas passage in the setting in communication with said furnace gas outlet and setting gas outlet, tubular means in the setting disposed in heat exchange relationship with gases of combustion passing to said :setting gas outlet, a portion of said tubular members extending outside said setting, an air-tight casing enclosing the portion of said tubular members extending-outside said setting, a source of fluid under pressure, fluid supply means in communication with said fluid source and casing, fluid discharge means in communication with said casing and the atmosphere, damper means for controlling the flow of fluid through said fluid supply means, other damper means for controlling the flow of fluid through said fluid discharge means, damper actuating means drivably connected to said damper and other damper means, said damper actuating means being operable in one direction to move the first-mentioned damper means toward an opened position and said other damper means toward a closed position and being operable in another direction to move the first-mentioned damper means toward a closed position and said other damper means toward an opened position, and pressure responsive means operable in response to changes in differential pressure between said casing and said setting for moving said damper actuating means in said one direction when the desired pressure differential changes by reason of an increase in pressure in the setting and adapted to move said damper actuating means in another direction when the desired pressure differential changes by reason of a decrease in pressure in the setting.

3. in a vapor generator, a setting having a gas outlet therein and including a roof, floor, side and rear walls, a furnace chamber in the setting having a gas outlet therein, means for firing the furnace, a gas passage in the setting in communication with said furnace and setting gas outlets, tubular members in the furnace in heat exchange relationship with gases of combustion passing to said 6 furnace "gas outlet, a portion of said tubular members extending above the setting roof, a steam and water drum positioned above the setting roof and in communication with said portion of tubular members, another portion of said tubular members extendings below the setting floor, other tubular members in the gas passage in heat exchange relationship with gases of combustion passing to said setting gas outlet, a portion of said other tubular members extending outside the rear wall of the setting, a plurality of air-tight casings enclosing the portion of tubular members and drum above the setting roof, the other portion of tubular members extending below the setting floor, and the portion of other tubular members extending outside the rear wall of the setting, a source of fluid under pressure, fluid supply means in communication with said fluid source and with each of said casings, fluid discharge means in communication with each of said casings and the atmosphere, damper means for controlling the flow of fluid through said fluid supply means, other damper means for controlling the flow of fluid through said fluid discharge means, and pressure control means for each of said casings for maintaining a desired differential pressure between each casing and the interior of the setting adjacent the casings, said pressure control means being adapted to move said first-mentioned damper means to an opened position and said other damper means to a closed position when the desired pressure differential changes by reason of an increase in pressure in the settin and adapted to move said first-mentioned damper means to a closed position and said other damper means to an opened position when the desired pressure differential changes by reason of a decrease in the setting.

4. In a vapor generator, a setting having a gas outlet opening therein, a furnace in the setting, means for firing the furnace, said furnace having a gas outlet opening therein, a gas passage in the setting in communication with said furnace gas outlet and setting gas outlet, tubular means in the setting disposed in heat exchange relationship with gases of combustion passing to said setting gas outlet, a portion of said tubular members extending outside said setting, an air-tight casing enclosing the portion of said tubular members extending outside said casing, a source of fluid under pressure, fluid supply means in communication with said fluid source and casing, fluid discharge means in communication with said casing and the atmosphere, damper means for controlling the flow of fluid through said fluid supply means, other damper means for controlling the flow of fluid through said fluid discharge means, pressure control means for maintaining a desired pressure differential between said casing and setting, said pressure control means comprising a rigid pressure vessel, a flexible diaphragm in the vessel forming two fluid-tight compartments therein, one of said two compartments being in communication with said casing, the other or". said two compartments being in com munication with the setting, and damper actuating means drivably connected to both said damper means and operative in response to departure from the desired diiferential of the pressures in both said compartments for moving the first-mentioned damper means to a closed position and the other damper means to an opened position when the desired pressure differential changes by reason of a decrease in pressure in the setting, and for moving the first-mentioned damper means to an opened position and the other damper means to a closed position when the desired pressure diflerential changes by reason of an increase in pressure in the setting.

5. In a vapor generator, a setting having a gas outlet opening therein, a furnace in the setting, means for firing the furnace, means for supplying air to said setting for supporting combustion therein, said furnace having a gas outlet opening therein, a gas passage in the setting in communication with said furnace gas outlet and setting gas outlet, tubular means in the setting disposed in heat exchange relationship with gases of combustion passing to said setting gas outlet, a portion of said tubular members extending outside said setting, an airtight casing enclosl the portion of said tubular members extending outside said setting, other means for supplying fluid to said casing, fluid discharge means in communication with said casing and the atmosphere, valve means in said other means for controlling the flow of fluid to said casing, second valve means in said fluid discharge means for con trolling the flow of fluid from said casing, and pressure control means responsive both to the fluid pressure Within said setting and Within said casing for operating both of said valve means to maintain a desired pressure differential between the pressure in the casing and the pressure in the setting to thereby obviate fluid leakage from the setting to said casing, adjacent said extending tubular portions.

6. In a vapor generator, a setting having a gas outlet opening therein, a furnace in the setting, burner means for firing the furnace, said furnace'having a gas outlet opening therein, means for supplying air under pressure to said setting for supporting combustion therein, a gas passage in the setting in communication with said furnace gas outlet and setting gas outlet, tubular members in the setting disposed in heat exchange relationship with gases of combustion passing to said setting gas outlet, a portion of said tubular members extending outside of said setting, an air-tight casing forming a chamber enclosing the portion of said tubular members extending outside of said setting, a source of fluid under pressure, fluid supply means in communication with said fluid source and casing to conduct the fluid to said casing, a fluid dis-charge conduit in communication with saidtcasing and the atmosphere, valve means in said fluid supply means for controlling the flow of fluid through the latter into the casing, second valve means in said fluid discharge means for controlling the flow of fluid from said casing to the atmosphere, and pressure control means responsive both to the combustion gas pressure within said setting and to the fluid pressure within said casing for operating both of said valve means to maintain the fluid pressure in said casing above the combustion gas pressure within the setting to thereby obviate leakage of combustion gases from the setting to said casing between said extending tubular portions and the setting,

References Cited in the file of this patent UNITED STATES PATENTS Re. 21,804 Gorrie May 20, 1941 660,557 Burger et a1 Oct. 30, 1900 1,819,174 Jacobus Aug. 18, 1931 1,908,547 Simmons May 9, 1933 2,083,504 Pugsley June 8, 1937 2,121,537 Coghill June 21, 1938 2,251,014 Firshing July 29, 1941 2,568,024 Pfenninger Sept. 18, 1951 

